I'm having an issue I'm hoping people here can help me with. After having completed the Building World for the first time, I was then able to enter the Apartment World. I entered Room 301 and realized I couldn't carry the Red Paper because my inventory was full so I went back to my apartment through the hole, there I found a new diary entry under the door and the bloody dryer. I also took a peek into Eileen's room and it said she was gone and that Henry hoped that she was okay.

Unfortunately, I lost my progress and had to restart from an earlier save but when I checked the hole into Eileen's room again, Eileen was there each time in a dress. What happened? How do I make it so that Eileen is gone (like originally)? Is Eileen's actions randomized and will this have an effect on the ending? I have tried quite a few times to recreate the original playthrough but I have had no luck in getting the original results.

If you check on her often you can see she carrying on with her life as usual. Taking out the trash, relaxing, cleaning her room... Complaining about a party... The same can be said to the other neighbours. Their daily actions don't affect the gameplay.

I don't want to spoil it for you since it seems you're playing the game for the first time, but other neighbours tend to "vanish" too, as the game goes on and on.

And I'm not aware of any specific pattern but it seems like. For me it always went from her doing random home cleaning, complaining about a party, dressing for the party, more random work, not showing up at all, random work, not showing up at all... And then, a "surprise"